1. Field of the Invention
The present invention relates to a content management system for managing content as electronic data, and more particularly to a content management system for storing content in an exchangeable storage medium and managing the original content.
2. Description of the Related Art
Due to recent developments in information processing systems, documents, diagrams, and other such content stored on paper has begun to be stored as electronic data. Because such electronic data can be easily changed, the original must be managed as electronic data.
Electronic data must therefore be provided with the following original attributes to enable content management of electronic data: first, a function that makes it possible to detect that the original electronic data has not been altered; second, a function that prevents third parties from unauthorized viewing of the electronic data; third, a history management function for the actual steps involved in the handling of the original electronic data; fourth, a function that makes it possible to trace the contents of each version or any changes in the original; and fifth, a function for guaranteeing the uniqueness of the original.
According to such requirements, in order to prevent tampering, a file server stores an electronic data, has an authority to access the file server (passwords and the like), and logs the operating history. While this method can prevent the original from being altered, it is still difficult to manage revisions to the original or to guarantee uniqueness of the original. For example, when electronic data is copied, it is unclear which original the copied data corresponds to.
It has therefore been proposed that electronic data of each edition be saved on the hard disk or other such internal storage device of a file server, that the revision number history of each edition be saved, and that original attributes (which signify that the original has not been altered) of electronic data on a file server be guaranteed (for example, Japanese Patent Application Laid-open No. 2002-82821).
However, the above-mentioned proposal is concerned with saving electronic data in a storage device of a file server, so the electronic data must be saved on an external storage medium and is divided between the internal storage medium and external storage medium when the volume of the electronic data surpasses the capacity of the storage device, complicating the system for managing the original. A specific drawback is that existing expandability is insufficient to handle an increase in the volume of electronic data (original).
The original attributes of electronic data are difficult to manage when the electronic data is saved on an external storage medium. Specifically, saving electronic data on an external storage medium allows the original to be taken out because of the nature of the external storage medium, making it difficult to manage the original and to distribute reproductions of the original while protecting the original or the copyright.